i have just had a cam belt change with all the tensioners and the water pump etc and also the fan belt

and now im having problems! it will start and run and idle okish but not like before the cambelt change, its producing white smoke and if i rev it hard it will throw out loads of smoke and a eggy unburnt fuel smell,also the idle will randomly drop time to time... the exhaust is blowing quite badly at the backbox but it was already like that...

something isnt right :( i thought it might be the lambda sensor but its not throwing the engine management light at me?

i went back to the garage and they said they would re check the belts for me so maybe its something to do with that as it is a big coincidence as it never missed a beat before hand